Apparatus for controlling temperature of electrostatic chuck comprising two-stage refrigerant fluid channel

ABSTRACT

An apparatus for controlling the temperature of an electrostatic chuck is provided. The apparatus includes an electrostatic chuck including, as a fluid channel part for circulating a refrigerant, a first fluid channel formed in an outer circumference region of the internal and a second fluid channel formed in the whole internal region, and one or more chillers for supplying refrigerant controlled to different temperatures through the first fluid channel or the second fluid channel. The first and second fluid channels are formed in two up/down stages within the electrostatic chuck, thereby being independently capable of the temperatures of a center part and edge part of a wafer.

CROSS REFERENCE

This application claims foreign priority under Paris Convention and35U.S.C. §119 to Korean Patent Application No. 10-2009-0135449, filedDec. 31, 2009 with the Korean Intellectual Property Office.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the temperature control of anelectrostatic chuck. More particularly, the present invention relates toan apparatus for controlling the temperature of an electrostatic chuckincluding a two-stage refrigerant fluid channel, for independentlycontrolling the temperatures of a center part and edge part of a waferby forming a first fluid channel of a plane spiral shape for the wholeinternal of the electrostatic chuck and a second fluid channel of aplane spiral shape for an outer circumference region of the internal ofthe electrostatic chuck, in two up/down stages.

2. Description of the Related Art

In general, a semiconductor device is obtained by realizing anelectronic circuit device through a process of patterning a conductivelayer and an insulating layer on a surface of a wafer fixed by anelectrostatic force of an electrostatic chuck. In addition to the roleof fixing the wafer, the electrostatic chuck is used as a plasmagenerating electrode. In case that ions and the like generated within achamber are accelerated and incident on a semiconductor substrate, thetemperature of the semiconductor substrate increases because kineticenergy of the ions and the like is converted into thermal energy. Such athermal change of the wafer induces the dispersion of a CriticalDimension (CD) within the wafer. Thus, in general, the electrostaticchuck is constructed to have a temperature control system. Thistemperature control system can be one chiller or can be a combination ofone chiller and a heater.

Temperature control using the combination of one chiller and the heaterprovides an advantage of being capable of independently controlling thetemperatures of a center part and edge part of a wafer but causesproblems that, because the heater should be inserted, the design of theelectrostatic chuck and a manufacturing process become complex and, incase of using high bias power as in an oxide etching process, the heateris damaged or a Radio Frequency (RF) noise leads to making controlcomplex and difficult.

Also, in case of using one chiller, there is a problem of not beingcapable of uniformly and rapidly controlling the whole temperature of awafer. Particularly, as a CD becomes smaller to 30 nm, a semiconductormanufacturing process becomes complex and in addition, a processcondition requires very precise control. Thus, in case of using only onechiller, it cannot perform precise control. As one example, there can bea Spacer Patterning Technology (SPT) or a Double Patterning Technology(DPT). Regarding an Amorphous Carbon Layer (ACL) or polycrystallinesilicon film, the former SPT process is performed at a high temperatureof more than 40° C. Regarding an oxide film, the former SPT process isperformed at a low temperature of less than 40° C. Thus, when respectivelayers are successively etched, a desired etching characteristic cannotbe obtained in case that all processes are performed at the sametemperature. Accordingly, in order to perform an in-situ process withoutgetting the wafer out of a chamber, there is a need to rapidly changethe temperature of the electrostatic chuck within a short time accordingto the form and quality of a film during an etching process.

Also, when the temperature of the electrostatic chuck is controlledusing only one chiller, the temperatures of the center part and edgepart of the wafer cannot be independently controlled. That is, it wasrequired that a CD distribution be controlled 2 nm or less in a processof a CD of 40 nm or less, but it appears that the CD distribution isreduced to 1 nm or less in a process of a CD of 30 nm or less.Accordingly, in order to meet this process condition, there is a need toindependently control the temperatures of the center part and edge partof the wafer.

SUMMARY OF THE INVENTION

An aspect of exemplary embodiments of the present invention is toaddress at least the problems and/or disadvantages and to provide atleast the advantages described below. Accordingly, an aspect ofexemplary embodiments of the present invention is to provide anapparatus for controlling the temperature of an electrostatic chuckincluding a two-stage refrigerant fluid channel, for independentlycontrolling the temperatures of a center part and edge part of a wafer.

Another aspect of exemplary embodiments of the present invention is toprovide an apparatus for controlling the temperature of an electrostaticchuck including a two-stage refrigerant fluid channel, for rapidlychanging the temperature of the electrostatic chuck even during aprocess progress.

According to one aspect of the present invention, apparatus forcontrolling the temperature of an electrostatic chuck is provided. Theapparatus may include an electrostatic chuck and one or more chillers.The electrostatic chuck includes a first fluid channel and a secondfluid channel as a fluid channel part for circulating a refrigerant. Thefirst fluid channel is formed in an outer circumference region of theinternal of the electrostatic chuck. The second fluid channel is formedin the whole region of the internal of the electrostatic chuck. Thechillers supply refrigerant controlled to different temperatures throughthe first fluid channel or the second fluid channel.

The first fluid channel and the second fluid channel may be formed intwo up/down stages within the electrostatic chuck, and may be shaped ina plane spiral structure.

Between the chiller and the fluid channel part, the apparatus mayfurther include an opening/closing valve for controlling the flow ofrefrigerant between the chiller and the fluid channel part, and acirculating valve for returning refrigerant flowing out from thechiller, and only internally circulating the refrigerant.

The circulating valve may be installed between the chiller and theopening/closing valve.

As described above, the present invention can independently control thetemperatures of a center part and edge part of a wafer by forming afirst fluid channel of a plane spiral shape for the whole internal ofthe electrostatic chuck and a second fluid channel of a plane spiralshape for an outer circumference region of the internal of theelectrostatic chuck, in two up/down stages.

Also, the present invention can rapidly change the temperature of theelectrostatic chuck even during the process progress by supplyingrefrigerant of different temperatures through a plurality of chillers.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the presentinvention will become more apparent from the following detaileddescription when taken in conjunction with the accompanying drawings inwhich:

FIG. 1 is a diagram illustrating a construction of a temperature controlapparatus according to a first exemplary embodiment of the presentinvention;

FIG. 2 is a flow diagram illustrating a temperature control methodaccording to FIG. 1;

FIG. 3 is a diagram illustrating a construction of a temperature controlapparatus according to a second exemplary embodiment of the presentinvention;

FIG. 4 is a flow diagram illustrating a temperature control methodaccording to FIG. 3;

FIG. 5 is a diagram illustrating a construction of a temperature controlapparatus according to a third exemplary embodiment of the presentinvention;

FIG. 6 is a flow diagram illustrating a temperature control methodaccording to FIG. 5; and

FIG. 7 is a top-view plane diagram illustrating a shape of a refrigerantfluid channel according to an exemplary embodiment of the presentinvention.

Throughout the drawings, the same drawing reference numerals will beunderstood to refer to the same elements, features and structures.

DETAILED DESCRIPTION OF THE INVENTION

Exemplary embodiments of the present invention will now be described indetail with reference to the annexed drawings. In the followingdescription, a detailed description of known functions andconfigurations incorporated herein has been omitted for conciseness.

FIG. 1 is a diagram illustrating a construction of a temperature controlapparatus according to a first exemplary embodiment of the presentinvention, and is a case including one refrigerant fluid channel and twochillers connecting to the refrigerant fluid channel. FIG. 2 is a flowdiagram illustrating a temperature control method according to FIG. 1.

Referring to FIG. 1, the temperature control apparatus 100 according tothe first exemplary embodiment of the present invention includes anelectrostatic chuck 101, a refrigerant fluid channel 102 formed withinthe electrostatic chuck 101 and circulating refrigerant flowing out froma plurality of chillers, two chillers 110 and 120 set to differenttemperatures, and a plurality of valves 110 a, 110 b, 110 c, 120 a, 120b, and 120 c for controlling the flow of refrigerant between the twochillers 110 and 120 and the refrigerant fluid channel 102. Although notillustrated in FIG. 1, a separate micro computer can be constructed toset the temperatures of the chillers 110 and 120 according to processand control the opening/closing of the plurality of valves 110 a, 110 b,110 c, 120 a, 120 b, and 120 c.

As illustrated in FIG. 1, the refrigerant fluid channel 102 is formedthrough the whole internal region of the electrostatic chuck 101. Arefrigerant is introduced into an inlet 102 a formed in a bottom part ofthe electrostatic chuck 101, and flows in the whole internal region ofthe electrostatic chuck 101 via the refrigerant fluid channel 102, andflows out via an outlet 102 b formed in the bottom part of theelectrostatic chuck 101.

The chillers 110 and 120 are devices for controlling the temperature ofrefrigerant according to a set temperature. The first chiller 110 is setto temperature (T₁), and the second chiller 120 is set to temperature(T₂).

The plurality of valves 110 a, 110 b, 110 c, 120 a, 120 b, and 120 ccontrol the flow of refrigerant between the chillers 110 and 120 and therefrigerant fluid channel 102 of the electrostatic chuck 101. Among thevalves 110 a, 110 b, and 110 c connecting to the first chiller 110, thevalve (V₁) 110 a is used for again returning refrigerant flowing outfrom the first chiller 110, to the first chiller 110. Among the valves110 a, 110 b, and 110 c connecting to the first chiller 110, the valve(V₂) 110 b and the valve (V₃) 110 c are used for controlling the flow ofrefrigerant between the first chiller 110 and the refrigerant fluidchannel 102. Similarly, among the valves 120 a, 120 b, and 120 cconnecting to the second chiller 120, the valve (V₄) 120 a is used foragain returning refrigerant flowing out from the second chiller 120, tothe second chiller 120. Among the valves 120 a, 120 b, and 120 cconnecting to the second chiller 120, the valve (V₅) 120 b and the valve(V₆) 120 c are used for controlling the flow of refrigerant between thesecond chiller 120 and the refrigerant fluid channel 102. Thisconstruction can efficiently change the temperature of the electrostaticchuck 101 within a short time according to the form and quality of afilm during an etching process even without getting a wafer out of achamber.

A temperature control method of the above-constructed temperaturecontrol apparatus is described in detail with reference to FIG. 2.

Referring to FIGS. 1 and 2, in step 200, the apparatus sets the firstchiller 110 to temperature (T₁), and opens the valve (V_(I)) 110 a andsimultaneously closes the valve (V₂) 110 b and the valve (V₃) 110 c. So,a refrigerant is controlled to the temperature (T₁) and circulates inthe first chiller 110 in itself.

Similarly, in step 201, the apparatus sets the second chiller 120 totemperature (T₂), and opens the valve (V₄) 120 a and simultaneouslycloses the valve (V₅) 120 b and the valve (V₆) 120 c. So, a refrigerantis controlled to the temperature (T₂) and circulates in the secondchiller 120 in itself.

In step 202, the apparatus judges whether to circulate the refrigerantof the first chiller 110 at the set temperature (T₁) according toprocess. If circulating the refrigerant of the first chiller 110 at thetemperature (T₁), the apparatus proceeds to step 203 and, otherwise,proceeds to step 205 and circulates the refrigerant of the secondchiller 120 at the temperature (T₂).

In step 203, the apparatus closes the valve (V₁) 110 a andsimultaneously opens the valve (V₂) 110 b and the valve (V₃) 110 c. So,the refrigerant controlled to the temperature (T₁) circulates in theelectrostatic chuck 101 through the refrigerant fluid channel 102.

After that, in step 204, the apparatus performs a corresponding processin an environment of the temperature (T₁).

In step 205, the apparatus closes the valve (V₄) 120 a andsimultaneously opens the valve (V₅) 120 b and the valve (V₆) 120 c. So,the refrigerant controlled to the temperature (T₂) circulates in theelectrostatic chuck 101 through the refrigerant fluid channel 102.

After that, in step 206, the apparatus performs a corresponding processin an environment of the temperature (T₂).

Lastly, if there is a need to perform a process in an environment of adifferent temperature in step 207, the apparatus proceeds to step 208and sets temperatures (T₁) and (T₂), repeating steps 200 to 207. Ifthere is no need to perform the process otherwise, the method isterminated.

FIG. 3 illustrates a construction of a temperature control apparatusaccording to a second exemplary embodiment of the present invention, andis a case including two refrigerant fluid channels and two chillersconnecting to the two refrigerant fluid channels. FIG. 4 is a flowdiagram illustrating a temperature control method according to FIG. 2.The temperature control apparatus 300 of FIG. 3 has the sameconstruction as the temperature control apparatus 100 of FIG. 1excepting that refrigerant fluid channels 302 and 303 are formed in twoup/down layers within an electrostatic chuck 301.

The refrigerant fluid channels 302 and 303 formed within theelectrostatic chuck 301 are described in more detail. The refrigerantfluid channels 302 and 303 are composed of a first refrigerant fluidchannel 302 formed at a top part of the electrostatic chuck 301 and asecond refrigerant fluid channel 303 formed at a bottom part of theelectrostatic chuck 301. The first refrigerant fluid channel 302 isformed in an outer circumference region of the internal of theelectrostatic chuck 301. The second refrigerant fluid channel 303 isformed through the whole internal region of the electrostatic chuck 301.This construction can independently control the temperatures of a centerpart and edge part of a wafer as described in detail in the descriptionof the related art. On the other hand, FIG. 3 illustrates that the firstrefrigerant fluid channel 302 is positioned above the second refrigerantfluid channel 303, but this is merely an exemplary implementation.According to need, the first refrigerant fluid channel 302 may bepositioned below the second referent fluid channel 303.

Referring to FIGS. 3 and 4 below, in step 400, the apparatus sets thefirst chiller 310 to temperature (T₁), and opens the valve (V₁) 310 aand simultaneously closes the valve (V₂) 310 b and the valve (V₃) 310 c.So, a refrigerant is controlled to the temperature (T₁) and circulatesin the first chiller 310 in itself.

Similarly, in step 401, the apparatus sets the second chiller 320 totemperature (T₂), and opens the valve (V₄) 320 a and simultaneouslycloses the valve (V₅) 320 b and the valve (V₆) 320 c. So, a refrigerantis controlled to the temperature (T₂) and circulates in the secondchiller 320 in itself.

In step 402, the apparatus judges whether to circulate the refrigerantof the second chiller 320 at the set temperature (T₂) according toprocess. If circulating the refrigerant of the second chiller 320 at thetemperature (T₂), the apparatus proceeds to step 403 and, otherwise,jumps to step 407, judging whether to perform a next process.

In step 403, the apparatus closes the valve (V₄) 320 a andsimultaneously opens the valve (V₅) 320 b and the valve (V₆) 320 c. So,the refrigerant controlled to the temperature (T₂) circulates in theelectrostatic chuck 301 through the refrigerant fluid channel 303.

After that, in step 404, the apparatus judges if there is a need to setan edge part of a wafer to a different temperature. The judgment can beimplemented through a separate micro computer not illustrated in FIG. 3.As the judgment result, if there is the need to set the edge part to thedifferent temperature, the apparatus proceeds to step 405 and,otherwise, jumps to step 406 and performs a corresponding process.

In step 405, the apparatus closes the valve (V₁) 310 a andsimultaneously opens the valve (V₂) 310 b and the valve (V₃) 310 c inorder to control the temperature of the edge part. So, the refrigerantcontrolled to the temperature (T₂) circulates in the electrostatic chuck301 through the refrigerant fluid channel 302 of the top part.

After that, in step 406, the apparatus performs a corresponding process.

After the corresponding process is performed, in step 407, the apparatusjudges whether there is a need to perform a process in a differenttemperature environment. If there is the need to perform the process inthe different temperature environment in step 407, the apparatusproceeds to step 408 and sets temperatures (T₁) and (T₂), repeatingsteps 400 to 406. If there is no need to perform the differenttemperature process otherwise, the method is terminated.

FIG. 5 illustrates a construction of a temperature control apparatusaccording to a third exemplary embodiment of the present invention, andis a case including two refrigerant fluid channels and three chillersconnecting to the two refrigerant fluid channels. FIG. 6 is a flowdiagram illustrating a temperature control method according to FIG. 5.The temperature control apparatus 500 of FIG. 5 is a combination of thetemperature control apparatus 100 of FIG. 1 and the temperature controlapparatus 300 of FIG. 3.

Referring to FIGS. 5 and 6, in step 600, the apparatus sets a firstchiller 510 to temperature (T₁), and opens a valve (V₁) 510 a andsimultaneously closes a valve (V₂) 510 b and a valve (V₅) 510 c. So, arefrigerant is controlled to the temperature (T₁) and circulates in thefirst chiller 510 in itself.

Similarly, in step 601, the apparatus sets a second chiller 520 totemperature (T₂), and opens a valve (V₄) 520 a and simultaneously closesa valve (V₅) 520 b and a valve (V₆) 520 c. So, a refrigerant iscontrolled to the temperature (T₂) and circulates in the second chiller520 in itself.

Similarly, in step 602, the apparatus sets a third chiller 530 totemperature (T₃), and opens a valve (V₇) 530 a and simultaneously closesa valve (V₈) 530 b and a valve (V₉) 530 c. So, a refrigerant iscontrolled to the temperature (T₃) and circulates in the second chiller530 in itself.

In step 603, the apparatus judges whether to circulate the refrigerantof the second chiller 520 at the set temperature (T2) according toprocess. If circulating the refrigerant of the second chiller 520 at thetemperature (T₂), the apparatus proceeds to step 604 and, otherwise,jumps to step 606, judging whether to perform a next process.

In step 604, the apparatus closes the valve (V₄) 520 a andsimultaneously opens the valve (V₅) 520 b and the valve (V₆) 520 c. So,the refrigerant controlled to the temperature (T₂) circulates in theelectrostatic chuck 501 through a refrigerant fluid channel 503.

On the other hand, in step 606, the apparatus closes the valve (V₇) 530a and simultaneously opens the valve (V₈) 530 b and the valve (V₉) 530c. So, the refrigerant controlled to the temperature (T₃) circulates inthe electrostatic chuck 501 through the refrigerant fluid channel 503.

After that, in step 605, the apparatus judges if there is a need to setan edge part of a wafer to a different temperature. Similarly, thejudgment can be implemented through a separate micro computer notillustrated in FIG. 3. As the judgment result, if there is the need toset the edge part to the different temperature, the apparatus proceedsto step 607 and, otherwise, jumps to step 608 and performs acorresponding process.

In step 607, the apparatus closes the valve (V₁) 510 a andsimultaneously opens the valve (V₂) 510 b and the valve (V₃) 510 c inorder to control the temperature of the edge part. So, the refrigerantcontrolled to the temperature (T₂) circulates in the electrostatic chuck501 through the refrigerant fluid channel 502 of the top part.

After that, in step 608, the apparatus performs the correspondingprocess.

After the corresponding process is performed, in step 609, the apparatusjudges whether there is a need to perform a process in a differenttemperature environment. If there is the need to perform the process inthe different temperature environment in step 607, the apparatusproceeds to step 610 and sets temperatures (T₁), (T₂), and (T₃),repeating steps 600 to 608. If there is no need to perform the differenttemperature process otherwise, the method is terminated.

FIG. 7 is a top-view plane diagram illustrating a shape of a two-stagerefrigerant fluid channel according to an exemplary embodiment of thepresent invention.

As illustrated in FIG. 7, the refrigerant fluid channel is composed of afirst refrigerant fluid channel 702 and a second refrigerant fluidchannel 703. The first refrigerant fluid channel 702 is formed at anupper layer along an outer circumference region of the internal of anelectrostatic chuck 701. The second refrigerant fluid channel 703 isformed at a lower layer throughout the internal of the electrostaticchuck 701. A refrigerant is introduced via a refrigerant inlet 702 a ofthe first refrigerant fluid channel 702, and flows along the outercircumference region of the internal of the electrostatic chuck 701, andflows out via a refrigerant outlet 702 b. On the other hand, arefrigerant is introduced via a refrigerant inlet 703 a of the secondrefrigerant fluid channel 703, and flows along the whole region of theinternal of the electrostatic chuck 701, and flows out via a refrigerantoutlet 703 b. The refrigerant fluid channel 701 is, as illustrated inFIG. 7, constructed to have a plane spiral-shape structure, but this ismerely an exemplary implementation, and the refrigerant fluid channel701 may be constructed in various forms according to the need of thoseskilled in the art. Also, the present invention illustrates that thefirst and second refrigerant fluid channels run on the upper layer andthe lower layer within the electrostatic chuck 701 but, according to anexemplary implementation, the first and second refrigerant fluidchannels 702 and 703 may be formed at one layer. Also, the firstrefrigerant fluid channel 702 may be constructed to have a greaterradius than the second refrigerant fluid channel 703, and the secondrefrigerant fluid channel 703 may be constructed to have a greaterradius than the first refrigerant fluid channel 702.

While the invention has been shown and described with reference to acertain preferred embodiment thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims.

1. An apparatus for controlling the temperature of an electrostaticchuck, the apparatus comprising: an electrostatic chuck comprising afirst fluid channel and a second fluid channel as a fluid channel partfor circulating a refrigerant, the first fluid channel being formed inan outer circumference region of the internal of the electrostaticchuck, and the second fluid channel being formed in the whole region ofthe internal of the electrostatic chuck; and one or more chillers forsupplying refrigerant controlled to different temperatures through thefirst fluid channel or the second fluid channel.
 2. The apparatus ofclaim 1, wherein the first fluid channel and the second fluid channelare formed in two up/down stages within the electrostatic chuck.
 3. Theapparatus of claim 1, wherein the first fluid channel and the secondfluid channel are shaped in a plane spiral structure.
 4. The apparatusof claim 1, further comprising: between the chiller and the fluidchannel part, an opening/closing valve for controlling the flow ofrefrigerant between the chiller and the fluid channel part; and acirculating valve for returning refrigerant flowing out from thechiller, and only internally circulating the refrigerant.
 5. Theapparatus of claim 4, wherein the circulating valve is installed betweenthe chiller and the opening/closing valve.